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Lactate Dehydrogenase (LDH) Activity in Serum/Plasma

Published: August 9, 2026Updated: August 17, 2026

This test measures the activity of the enzyme lactate dehydrogenase (LDH), which plays a role in converting lactate to pyruvate during energy production in cells. LDH levels can help identify conditions affecting tissues where this enzyme is present.

Quick summary

["LDH helps diagnose and monitor conditions affecting cells, including heart, liver, and muscle damage."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
2537-9
Short code
LDH1 SerPl-cCnc
Synonyms
LDH1 SerPl-cCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
140
Ref high
280
Critical range
— – 1000 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
83615
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What Is LDH Used For?

LDH is commonly used to detect and monitor conditions such as heart attacks (myocardial infarction), liver disease, red blood cell disorders, and certain cancers. It can also help assess muscle injuries or infections.

Why Might You Need This Test?

Your doctor may order an LDH test if you have symptoms like chest pain, unexplained fatigue, jaundice (yellowing of skin/eyes), muscle weakness, or if they suspect conditions like heart disease, liver problems, or blood disorders.

How Is the Test Performed?

A blood sample is drawn from a vein, usually in your arm. The sample is then sent to a lab where LDH activity is measured using an enzymatic method to detect how much of the enzyme is present in your serum or plasma.

What Are Possible Results?

Results are reported in units per liter (U/L) or other standardized units, but exact values depend on the lab. Elevated LDH may indicate tissue damage or disease, while normal levels suggest healthy enzyme activity.

Reference range

Adult: 140-280 U/LN/A

Specimen: serum

No special preparation required. Inform provider of any chest pain or symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

LDH Activity

Frequently asked questions

What causes elevated LDH levels?
Elevated LDH can result from conditions like heart attacks, liver disease, muscle injuries, infections, blood disorders, or certain cancers. It may also appear after trauma or surgery.
What does it mean if my LDH is normal?
If your LDH test result is within the normal range, it suggests your enzyme levels are healthy, but it doesn’t rule out all possible conditions. Your doctor may still recommend further testing if you have symptoms or risk factors.
Can lifestyle changes affect LDH levels?
Yes, lifestyle factors like intense exercise, muscle strain, or certain medications may temporarily affect LDH levels. However, chronic changes usually require medical evaluation to determine underlying causes.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 17, 2026. · Read our editorial policy